1. Field of the Invention
The present invention relates to a hybrid vehicle propulsion apparatus comprising an internal combustion engine having an output shaft and a motor generator coupled directly to the output shaft.
2. Description of the Related Art
There has been proposed a hybrid vehicle having an internal combustion engine for generating propulsive forces by combusting gasoline and a motor generator which can be operated as an electric generator for regenerating electric energy and an electric motor for generating propulsive forces with electric energy to assist propulsive forces produced by the internal combustion engine. The propulsive forces produced by the internal combustion engine and the electric motor are combined as required to propel the vehicle. For details, reference should be made to Japanese laid-open patent publication No. 9-156388.
In the proposed hybrid vehicle, a transmission is coupled to the crankshaft of the internal combustion engine through a flywheel and a clutch mechanism, and the motor generator is coupled to a drive gear of the transmission.
The motor generator incorporated in the proposed hybrid vehicle is of a relatively large size. Therefore, since the motor generator is coupled to the drive gear of the transmission, the entire propulsion apparatus is considerably large in size. The large propulsion apparatus poses no essential problem if it is incorporated in largesize vehicles such as buses because their engine compartment usually has an enough space for the large propulsion apparatus. However, it is difficult to combine the proposed propulsion apparatus with small-size vehicles such as ordinary passenger cars due to their requirements for lightweight and compact designs.
Conventional internal combustion engines are associated with many accessories including a compressor, an oil filter, etc. The oil pan fitted beneath the crankcase of an internal combustion engine is shaped in view of the layout of those accessories. If a motor generator, a clutch mechanism, etc. are connected to the internal combustion engine, then a connector such as a bracket is needed to couple the oil pan to the housing of the motor generator. As a result, the number of parts used is increased.